1.Field of the Invention
The present invention relates to a work position adjusting apparatus and a work position adjusting method for correcting an error in inclination of a work surface of a work, for example, and an error in rotation along the work surface on a work table of a machine tool.
2. Description of Related Arts
Referring to FIGS. 21 and 22, reference numeral 30 denotes a machine tool such as an NC milling machine. Reference numeral 31 denotes a work table on which a work is carried. An upper surface 32 of the work table 31 is basically parallel to an X-Y motion plane (hereinafter merely referred to as an X-Y plane) of a machine. In the case of FIG. 21, the work table 31 is movable upon being guided by an X-axis guide rail 37 and a Y-axis guide rail 38 on the X-Y plane of the machine. A work 33 is carried and fixed on the upper surface 32 of the work table 31 directly or through a work supporting device 34 such as a vice. A cutting tool 35 is mounted on a spindle and is rotated around a pindle center M to cut the work 33.
Referring to FIG. 22, at the time of working, a work surface 39 of the work 33 must be set in a correct positional relationship with the X-Y plane of the machine. In order to simplify the description, a case where the work surface 39 of the work 33 should be parallel to the X-Y plane will be hereafter premised. In this case, in such working that precision on the order of microns is required, the work surface 39 is not always completely parallel to the X-Y plane only by merely mounting the work 33 directly or through the work supporting device 34.
Specifically, the work surface 39 is not always completely parallel to the X-Y plane by accumulating various errors such as an error in inclination of a surface of the work table 31 itself and an error caused by the work supporting device 34, and generally, has an error in inclination on the order of microns (an error in the degree of parallelization). The work 33 has an error in rotation around an axis perpendicular to the X-Y plane. In either case, it is preferable that the error in inclination and the error in rotation are brought as close to zero as possible.
In the prior art, the error in inclination of the work surface 39 is measured prior to the working, and then the inclination is adjusted by lightly tapping a part of the work surface 39 of the work 33 or spreading a thin metal foil between a part of the bottom of the work 33 and a base metal 40, for example. The error in inclination on the order of microns is brought close to zero by repeating such operations of measuring and correcting the error.
The error in the degree of parallelization related to the above-mentioned error in rotation is measured, and is measured again after slightly loosening a bolt 41 for mounting the work supporting device 34 on the work table 31 and lightly tapping a side part of the work supporting device 34, thereby finely adjusting the degree of parallelization of the work supporting device 34. The error in the degree of parallelization on the order of microns is brought close to zero by repeating such an operation as mentioned above.
The operations are very troublesome, and the efficiency of the operations significantly depends on the skill of a worker.
Furthermore, human intervention is always required for the operations, which presents a large problem in the case of unmanned automation of the working including a set-up operation such as replacement of the work and fine adjustment of the inclination and the degree of parallelization.